1. Technical Field
This invention relates generally to static gaskets of the type used to establish a gas/fluid-tight seal between two members to be clamped together, such as a cylinder head gasket.
2. Related Art
In establishing a gas/fluid-tight seal between two members to be clamped together, such as between a cylinder head and cylinder block, it is common to use a static cylinder head gasket having one or more layers, referred to as a multilayer gasket. Generally, at least one of the layers of the multilayer gasket, sometimes referred to as a functional layer, has one or more seal beads to facilitate establishing a fluid tight seal. Another of the layers, sometimes referred to as a distance layer, is configured to abut the function layer to facilitate establishing the fluid tight seal. Upon being installed, contact stresses are typically established across the beads, wherein the contact stresses extend to an annular edge bounding the opening, e.g. cylinder bore, being sealed. Unfortunately, although providing an initially reliable seal, over time and while in use, damage can result to the surfaces being clamped and sealed against one another, thereby impacting the ability of the seal to remain air and/or fluid tight. This is particularly troublesome at peripheral edges being sealed, such as at a cylinder bore edge between the cylinder head and cylinder block. In use, the gasket undergoes cyclic stress cycles at the peripheral edge being sealed throughout each full stroke of a piston. The cyclical stresses result in relative movement of the gasket material against the respective surfaces being sealed, e.g. cylinder head and cylinder block. The movement of the gasket material against the mating surfaces thereby results in the aforementioned surface damage, such as by way of fretting. Accordingly, the ability of the seal assembly to maintain a reliable seal across the clamped surfaces is typically diminished over time.